meninges and dural venous sinusehkmu.online/.../uploads/2016/02/meninges-and-dural-veno… · ppt...

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MENINGES AND DURAL VENOUS SINUSE

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MENINGES

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• The brain in the skull is surrounded by three protective membranes, or meninges: the dura mater, the arachnoid mater, and the pia mater.

• (The spinal cord in the vertebral column is also surrounded by three meninges)

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Dura Mater of the Brain

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• The dura mater is conventionally described as two layers: the endosteal layer and the meningeal layer. These are closely united except along certain lines, where they separate to form venous sinuses.

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Dura Mater (meningeal layer)…

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• The meningeal layer is the dura mater proper. It is a dense, strong, fibrous membrane covering the brain and is continuous through the foramen magnum with the dura mater of the spinal cord. It provides tubular sheaths for the cranial nerves as the latter pass through the foramina in the skull. Outside the skull the sheaths fuse with the epineurium of the nerves.

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DURAL VENOUS SINUSES

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The venous sinuses…• The venous sinuses of the cranial cavity are blood-filled spaces

situated between the layers of the dura mater they are lined by endothelium. Their walls are thick and composed of fibrous tissue; they have no muscular tissue. The sinuses have no valves.

• Absorb the C.S.F through the arachnoid granulation tissue & Receive blood from cerebral veins and from valveless emissary veins

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Classification of Dural sinuses:The venous sinuses are classified into paired and unpaired groups:

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Unpaired sinuses:1.Superior sagittal sinus2.Inferior sagittal sinus3.Straight sinus4.Occipital sinus5.Anterior intercavernous sinus6.Posterior intercavernous sinus7.Basilar venous plexus

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Paired sinuses:1.Transverse2.Sigmoid sinus3.Cavernous sinus4.Superior petrosal sinus5.Inferior petrosal sinus6.Spheno-parietal sinus7.Petro-squamous8.Middle meningeal

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